Background: Analysis of safety data using randomized controlled trials is often challenging because events are typically rare. Various statistical methods have been proposed to model rare events in a frequentist setting. In a Bayesian framework, rare events can be modeled using the binomial likelihood. Evaluation of the comparative safety of endoscopic (ECTR) and open carpal tunnel release (OCTR) poses an additional challenge; the outcomes are often correlated because of bilateral involvement. Moreover, statements about the conclusiveness of evidence are difficult to draw when outcomes are rare.
Objectives: To evaluate whether there is evidence supporting a higher risk after ECTR in comparison to the conventional open release using a variety of methods to address rare events and developing a model for dichotomous correlated outcomes.
Methods: We included all randomized or quasi-randomized controlled trials in a systematic review and synthesised them in a meta-analysis. Safety was assessed by the incidence of major, minor and total number of complications, recurrences, and re-operations. Different methods to handle rare events and a Bayesian model were compared. A bivariate random-effects model was developed to account for the correlated events. We explored various methods to approximate correlation coefficients based on the number of patients with bilateral involvement. We applied three different methods to decide whether the evidence was conclusive.
Results: The assessment of major complications, reoperations and recurrence of symptoms does not favor either of the interventions and all models are consistent in their results. ECTR performs better in terms of minor complications compared to OCTR. Despite the fact that complications were rare, it is unlikely that future evidence will alter these conclusions.
Conclusions: Various statistical analyses for correlated and rare events did not suggest a significant benefit of one surgical technique over the other. The strength of evidence in favor of a clinically relevant difference is weak. Further studies are not likely to detect a difference between ECTR and OCTR in terms of safety outcomes.